terra (version 1.0-10)

classify: Classify (or reclassify) cell values

Description

Classify values of a SpatRaster. The function (re-)classifies groups of values to other values.

Classification can be based on ranges "from-to-becomes" or on specific values "is-becomes", or on "cuts".

With "from-to-becomes" or "is-becomes", classification is done with matrix rcl, in the row order of the matrix. Thus, if there are overlapping ranges or values, the first time a number is within a range determines the reclassification value.

With "cuts" the values are sorted, so that the order in which they are provided does not matter.

Usage

# S4 method for SpatRaster
classify(x, rcl, include.lowest=FALSE, right=TRUE, 
     othersNA=FALSE, filename="", overwrite=FALSE, wopt=list(), ...)

Arguments

x

SpatRaster

rcl

matrix for classification. This matrix must have 1, 2 or 3 columns. If there are three columns, the first two columns are "from" "to" of the input values, and the third column "becomes" has the new value for that range.

The two column matrix ("is", "becomes") can be useful for re-classifying integer values. In that case, the right argument is automatically set to NA.

A single column matrix or a vector is interpreted as a set of cuts. In that case the values are classified based on their location inbetween the cut-values

include.lowest

logical, indicating if a value equal to the lowest value in rcl (or highest value in the second column, for right=FALSE) should be included.

right

logical, indicating if the intervals should be closed on the right (and open on the left) or vice versa. The default is TRUE. A special case is to use right=NA. In this case both the left and right intervals are open

othersNA

logical. If TRUE, values that are not matched become NA. If FALSE, they retain their original value.

filename

character. Output filename. Optional

overwrite

logical. If TRUE, filename is overwritten

wopt

list. Options for writing files as in writeRaster

...

additional arguments. None implemented

Value

SpatRaster

Examples

# NOT RUN {
r <- rast(ncols=10, nrows=10)
values(r) <- (0:99)/99

## from-to-becomes
# classify the values into three groups 
# all values >= 0 and <= 0.25 become 1, etc.
m <- c(0, 0.25, 1,
       0.25, 0.5, 2,
       0.5, 1, 3)
rclmat <- matrix(m, ncol=3, byrow=TRUE)
rc1 <- classify(r, rclmat, include.lowest=TRUE)

## cuts
# equivalent to the above
rc2 <- classify(r, c(0, 0.25, 0.5, 1), include.lowest=TRUE)

## is-becomes 
x <- round(r*3)
unique(x)
# replace 0 with NA
y <- classify(x, cbind(0, NA))
unique(y)

# multiple replacements
m <- rbind(c(2, 200), c(3, 300))
m

rcx1 <- classify(x, m)
unique(rcx1)

rcx2 <- classify(x, m, othersNA=TRUE)
unique(rcx2)
# }

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